Yes, because all search engines - the big ones and smaller, single-site ones - are now expected to be "Googly". As in, the engine is supposed to know what you mean even if you don't know what you mean. Instead of relying on the user to punch in exactly what he's looking for and treating a search engine as an
inverse index, (
archive) it has become expected that every vague keyword is to expanded to mean more than what you typed based on context, that being other keywords in the query or based on some external knowledge on who the user is.
Being able to read the user's mind is great and everything but it opens dozens of avenues to fuck up even the simplest search query because computers are braindead. So unless you are Google and have everyone's information it means you have to do it in aggregate and make a best effort and hope the individual's vague query is close to the average on what the engine determines it to be.
Since we let retards onto the internet, though, that means if you actually
do know what you want, ask for it specifically, and it's not on the radar of the average moron, you're likely to get a poor result. And that's discounting any tampering the engine might be doing anyway.